In recent years, as portable electronic devices (e.g., mobile phones and digital cameras) become ubiquitous, much effort has been put into reducing dimensions of portable electronic devices. Moreover, as dimensions of charged coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) based optical sensors are reduced, dimensions of imaging lenses for use with the optical sensors must be correspondingly reduced without significantly compromising optical performance. However, the most important characteristics of imaging lenses are imaging quality and size.
Each of U.S. Pat. Nos. 8,355,215 and 8,432,619, and Taiwanese Patent Application Publication No. 201337319 discloses a relatively long conventional imaging lens that includes six lens elements. These conventional imaging lenses have a system length of over 6 mm, which is not reducible to be within a range that would satisfy thin design requirements for mobile phones.
Therefore, greater technical difficulties are encountered for a miniaturized imaging lens than for traditional imaging lenses. Producing an imaging lens that meets requirements of consumer electronic products while having satisfactory optical performance is always a goal in the industry.